When a device (e.g. a router, switch, access point, or any device) attempts to access an Application Programming Interface (API) resource hosted by an enterprise, it is often required that a human encode and save their login credentials (e.g., user identifier and user password) directly into the configuration of the device. The device then impersonates that human's user account when accessing the enterprise API resources. This is known as a password anti-pattern.
Saving a user's credentials on a device has many disadvantages. The credentials may not be secure at rest in the configurations. The credentials may or may not be secure in transport. Such is the case when Trivial File Transfer Protocol (TFTP) is used, or when the credentials are stored off-box, e.g., in a plain text file. The device could get stolen (while still configured with that user's credentials). The user's password could change (by policy or as a reaction to a password loss), which would result in the need to change the configurations on all devices that have stored that user's credentials. The user could leave the role or group or company. In any event, the device is not identifying itself; rather the device is posing/impersonating the saved user's identity.